Korea: US, ROK forces improve interoperability

In order to enhance tactical communications between United States Forces Korea and Republic of Korea Army, the 304th Signal Battalion invited the 63rd Signal Battalion to participate in the unit's Technical Exercise at Camp Colbern May 10-14, 2004. The intent of the exercise was to improve relations between the two signal battalions and create a seamless interface between the U.S. and ROK Army Networks.

The MSC-500K Spider Switch is an analog tactical deterministic switching system that provides tactical command, control, communications, computers and intelligence for ROKA.

System components consist of the AN/TTC-95K Node Management Terminal and cable assemblies. Compared to the United States Single Shelter Switch which operates on a local database and supports multiple wire line interfaces, the Spider does not operate on a local database; each trunk must be manually programmed and is limited to two-wire devices. The Spider terminates subscribers and internodal links with the same Junction Box. Internodal links are also installed via the signal entry panel using coxial cable.

In January 2000, the 8th U.S. Army conducted initial tests using the Spider Adapter Interfaces and the NATO Analog Interfaces to connect U.S. and ROKA Communications Networks. The SAI was fabricated as an interim connection device for the Spider. The interface was phased out due to equipment shortages. It required a one to one ratio of NAI to SAI; there were only two NAIs on the peninsula. Additional tests demonstrated the Spider to EAC/Mobile Subscriber Equipment switching systems interoperable, but dialing between the Spider and EAC/ MSE networks required a 13-digit dialing sequence (3-digit NATO code, 3-digit area code and the seven-digit number). Further tests conducted in December 2002 and June 2003, improved the SPIDER to U.S. dialing sequence from 13 to 10-digits. The U.S. to Spider dialing sequence was changed to Commercial Office (5C) effectively reducing the dialing sequence. However, the commercial office access poses several problems--

* When a subscriber dials 5C, the call is routed to the first available 5C programmed switch, not the necessarily in tended switch.

* Once a call exits the tactical network, it is impossible to reenter the same network.

* When a call is terminated, the switch does not always release the trunk, reducing access to the Spider.

The objectives of the training conducted between the 304th and 63rd Signal Battalions were to reduce the dialing sequence, conduct direct dialing from Spider to Spider via the U.S. tactical network without operator intervention, conduct secure call and facsimile operations eliminating 5C. In order to conduct the tests, two AN/TTC-56 Single Shelter Switches, two MSC-500K Spiders and two Line Termination Units were setup. The Spiders were connected to the LTUs via 12 pairs of WD-1. Six lines were for receiving and six lines for placing phone calls. Each pair is equivalent to a trunk. The LTU was connected to the SSS and a link was established between the SSS's. (See Diagram 1.)

At endstate, all objectives were accomplished, both systems were able to place calls by dialing seven-digits without the 5C prefix and the switch released all trunks. Direct dialing was performed from Spider to Spider via the U.S. tactical network without operator intervention from the SSS operator. While there was no intercept from the U.S. operator, all calls placed to the Spider required intervention from the ROKA operator to complete the call. This was due to the internal configuration of the Spider Switch and J-boxes.

This was a highly visible training event with visits from multiple VIP's including the 3rd ROKA AcoS C6, 1st Signal Brigade commander and members of the U.S. Forces Korea Joint Staff. Units have started planning to conduct training focusing on the ROKA operator intercept issue prior to Ulchi Focus Lens '04.

Following is a detailed chart on building the DTG and populating the LTU (see chart on Page 9).

AN/TTC-56(V) 1 Single Shelter Switch
Configuration and Programming

Programming:
DTG

DTG Number                  12
Starting Address         BS-LA
Number of Channels          32
TED Number                  No
Synchronization Delay      Yes
Channel Rate16            Kbps
Group Rate           576 Kbpps
Multiplex Signal Format      1
Subgroup 1 Rate              0
Subgroup 2 Rate              0
Subgroup 3 Rate              0
Service State               ln
Modulator Cable Length       3
Demodulator Cable Length   1/4
Modulation             Diphase
Repeater Mode               No
Red Group Clock             No
Recover Time                No
DTG Release Timer            0
Output Type             Normal

Subscriber Services:
Preaffiliation

Action                       2
List Number            (Blank)
Directory Number       LNXXXXX
(620-1211/12/14/15/16/17-use
spares to avoid affiliating
duplicate numbers) for slots
Al and A2 of the LTU
(Allows Spider to call U.S.)
(730-0001/2/3/4/5/6-provided
by the Spider operator) for
A4 and A6 of the LTU
(Allows US to Spider)
Profile Index              239
(for a1112 subscriber numbers)
Target Device      1=Load Disk

Affliation
Action                       1
Directory Number       LNXXXXX
(620-1211/12/13/14/15/16/17)
for slots Al and A2 of the LTU
(Allows Spider to call US)
730-001/2/3/4/5/6) for slots
A4 and A6 of the LTU (Allows
US to Spider)

TGC
TGC #                       16
TGC Type                 Other
Spill Forward               No
Destination NYX            806
Zone Restriction Number      0
Access Trunk Group         Yes
Traffic Limitations         No

Terminal Services
Terminal Address         XX-XX
(Use the BS-Las for the
2WLTU CCA located in slots
Al and A2 in the LTU)
Terminal Type               44
TGC Number                  16
Path Delay                   0
Satellite Trunk             No
Service State               ln
Dedicated Echo               0
Suppressor Number      (Blank)
Transmission Type       Analog
Non-Secure
Carrier Mode                No
Adapter Number 1(sequential)
DTLU                       Yes
T digit                     No
Bar in dailing              No

Loop Strapping
Terminal Address         XX-XX
(Use the BS-LA's for the
2WLTU CCA's located in
the LTU)
Terminal Type                8
(Enter for all 12 subscriber
numbers)
Phantom Loop Power         Yes
ADOCU Home Code        (Blank)

ACRONYM QUICKSCAN

C41--command, control, communications, computers and intelligence

DTG--Digital Transmission Group

J-Box--Junction Box

LTU--Line Termination Units

NAI--NATO Analog Interfaces

ROK--Republic of Korea

ROKA--Republic of Korea Army

SAI--Spider Adapter Interfaces

SSS--Single Shelter Switch

US--United States

USFK--United States Forces Korea

CW2 Stewart is with the 304th Signal Battalion, 1st Signal Brigade, Camp Colbern, Korea.

COPYRIGHT 2004 U.S. Army Signal Center
COPYRIGHT 2005 Gale Group